“In the absence of any lunar atmosphere, the Sun’s corpuscular radiation bombards the Moon’s crust, causing—uh—interference of the radio waves. This interference is what causes inter—”

He was floundering.

“The interference interferes—absolutely right!” said the commandant, coming to his aid. “But what causes the interference?”

“A secondary radiation, known as the No—the No—”

“Nov—” The commandant prodded gently.

“The… Novinsky effect!” Pirx finally blurted out. But the interrogation didn’t end there.

“And what produces the Novinsky effect?”

This last question had him altogether stumped. There was a time when he’d known the answer, but he had since forgotten. He had gone into the exam with the facts down cold, like a juggler balancing a pyramid of wildly improbable things in his head. But the exam was over now. He was desperately going on about electrons, forced radiation, and resonances when he was cut short by a sympathetic head-shake from the commandant.

“Uh-uh,” said the stern and uncompromising man. “And Professor Merinus gave you a B for the course… Hm. Do you suppose he might have made a mistake?”

Pirx’s armchair was slowly being transformed into a live volcano.

“I wouldn’t wish to cause my colleague any embarrassment, so I think the less said about this the better…”

Pirx sighed.

“But during your comprehensive examination I shall see to it that Professor Laab…”

He left the rest to Pirx’s imagination. Pirx gulped, but not from the concealed threat; the commandant’s hand was slowly scooping up the papers that were to have accompanied his Mission.

“Why isn’t a cable communications system practicable?”

“Too costly. At the moment only one concentric cable is in operation—the one connecting Luna Base with Archimedes. There are plans to install a cable network within the next five years,” Pirx fired away.